Frozen aerated confections, for example ice cream, sherbet, sorbet and frozen yoghurt, contain minute ice crystals and air bubbles. The size of the ice crystals and air bubbles affects the texture of the product. During frozen storage, ice crystals and air bubbles coarsen. Coarsening leads to deterioration in the texture. For example, when the ice crystals become very large (˜100 μm) they can be individually detected in the mouth and the texture becomes icy and gritty. Similarly large air bubbles result in ice cream having a less creamy texture. The rate of coarsening depends on the temperature: the higher the temperature, the faster the coarsening.
Ice structuring proteins (ISPs), also known as antifreeze proteins (AFPs), have been known for some years, and used in ice cream as a means of reducing ice crystal coarsening, especially following thermal abuse. EP0783254 describes a method for minimizing ice-crystal size in a frozen composition by adding an anti-freeze protein. However, ISPs do not prevent coarsening of the air bubbles during storage. Thus there remains a need for frozen aerated confections which are resistant to coarsening both of the ice crystals and the air bubbles.